Harnessing offshore wind while preserving the seas

Offshore wind energy — a sector mitigating climate change

To reduce Europe’s greenhouse gas emissions in line with the EU’s commitments under the Paris Agreement, European climate law sets a target to reach climate neutrality by 2050. An important milestone occurs in 2030 when Europe must meet a legally binding target of at least 55% net greenhouse gases emission reductions compared with 1990.

Together with increasing energy efficiency, shifting energy generation from fossil fuels to renewable sources is critical in this respect. The target is to increase renewable energy generation to at least 42.5% by 2030, with the aim to reach 45%. By comparison, Europe’s renewable energy share was 23% in 2022 (EEA, 2024a). As such, increased generation of renewable energy is a critical element of decarbonising Europe’s economy.

Offshore wind will have to be a significant contributor to achieve these targets. In 2023, the cumulative installed capacity of offshore wind in the EU was 19.38GW, with a noteworthy 3GW added during that year alone. As highlighted in the communication Delivering on the EU offshore renewable energy ambitions, the development of offshore wind energy capacity is foreseen to grow to 111GW of installed capacity by 2030 and 317GW by 2050 as agreed regionally by Member States (EC, 2020b, 2021a). The European Green Deal (EC, 2019) and the Offshore Renewable Energy Strategy in particular (Box 1), highlight how the development of renewable offshore wind can provide unique opportunities for industry growth and jobs across Europe’s coastal regions and beyond — in addition to renewable energy generation that helps shift Europe’s economy away from fossil fuel-based energy sources.

However, it did not yet address environmental aspects of developing offshore wind (ECA, 2023).

To achieve Europe's climate and energy security objectives, the production of renewable energy sources will need to accelerate substantially. For offshore wind, this will mean an average annual growth of 8.3GW from 2027 to 2030 and an average annual installation of 12GW from 2030 to 2050. With a current capacity to install 7GW per year, growth will clearly be needed within the sector to meet these targets (WindEurope, 2024). This includes expanding capacity across the offshore wind supply chain, including production facilities for turbines and foundations, access to materials (especially, enhancing circular approaches), infrastructure such as grids, storage capacity, ports, and vessels, and support for sustainable decommissioning. Such expansions have already begun across the supply chain in companies across Europe (WindEurope, 2024), alongside growth in jobs for maintenance, replacement and eventual decommissioning in coastal areas.  

In some locations that previously depended on jobs in the offshore oil and gas sector, this growth offers new opportunities. However, it is unclear whether EU industry can overcome supply chain constraints across all key technologies and activities needed to accelerate towards EU energy ambitions.

There will also be emerging opportunities, and challenges, with the large expansion of offshore wind energy from a circular economy perspective. Different types of waste will be generated as these large wind turbines reach the end of their life cycle. As such, there is a unique opportunity to anticipate how to handle decommissioning and the potential reuse of materials by applying circular economy principles already at this early development phase (EEA, 2021, 2024c). So far, there is little published information available on decommissioning of offshore windfarms (Lemasson et. al, 2022; Topham et al., 2019; van Maele et al. 2023). The first generation of offshore turbines comes to the end-of-life expectancy by 2025. (University of Kent, 2021).

The total area needed to develop offshore wind at the intended scale is difficult to determine, as the generation of offshore wind energy can be co-located with other activities such as fishing, aquaculture, maritime transport and some recreational activities. The spatial area also depends on the size and generation capacity of each turbine, which has grown in recent years, as well as the type of anchoring used.

In addition, the world's deepest wind turbine is installed at 58m depth, though floating turbines are being tested in deeper waters of 70m. This indicates that, with current technology the relevant conditions for offshore wind development in Europe are often located in shallower, more coastal areas, rather than across the full extent of the EU’s marine area (SSE, 2023).

Therefore, not all of EU maritime space is currently suitable for the placement of offshore wind energy, which depends on natural conditions like wind or depth to seafloor.

So far, EU Member States have planned for offshore wind development equivalent to more than 220GW or 52,000km² in their maritime spatial plans. The EU strategy on offshore renewable energy estimates that less than 3% of the total EU maritime space is needed to reach the EU’s targets for offshore wind (EC, 2020b).

Marine protected areas — a measure supporting the restoration of seas

The need to ensure the resilience of Europe’s marine habitats has never been greater, not least as coastal waters, seas and marine life face unprecedented pressure from climate change and numerous land and sea-based activities. January and February 2024 set new records as the warmest months recorded for the ocean accompanied by long-term heightened sea temperatures, and increased ocean acidification and deoxygenation (EEA, 2023a;  NOAA, 2024; UOM, 2024). The Offshore Renewable Energy Strategy acknowledges that there are big knowledge gaps on the cumulative impacts of offshore wind installations on marine ecosystems.

The EU has consistently worked to ensure the protection of its marine environment through initiatives like the Natura 2000 network (EEA, 2012, 2015a), with ambitions further strengthened by the current Biodiversity Strategy for 2030 and the Nature Restoration Law, which was recently adopted into law (Box 2). The EU therefore strives for both extensive renewable energy to mitigate climate change and protect vulnerable marine habitats, critical for carbon-rich habitats, biodiversity and resilience against climate change. Healthy coastal waters and seas remain essential for maritime sectors such as fisheries as well as for human well-being (H2020 SOPHIE Consortium, 2020; Fleming et al., 2024).

With the Biodiversity Strategy’s target of 10% of Europe’s seas being ‘strictly protected areas’ comes an additional challenge regarding the use of the coastal space. Currently, 9% of Europe’s seas are covered by the Natura 2000 network as designated by the Habitats Directive and the Birds Directive. Though these areas cannot be considered ‘strictly protected’, this network has been designated to protect Europe’s most vulnerable and sensitive species and habitats. The marine part of the network is predominantly designated within 0 to 12 nautical miles from the shore in zones where offshore turbines are often developed (ETC/ICM, 2020). In addition, EU Member States have designated about 3% of Europe’s seas as nationally protected areas under national laws.

Coastal areas in high demand

From an environmental perspective, coastal areas (defined under the Water Framework Directive as those areas not exceeding one nautical mile from the shore) are considered highly vulnerable, not only to climate change but also to the impacts of a variety of human activities and pressures (Map 1 and Map 2a). These include sea-based human activities in coastal areas including fisheries, marine aggregate extraction, maritime transport, submarine cables and pipelines, aquaculture, offshore wind, oil and gas exploitation, tourism and more. Land-based human activities also influence the marine environment via pollution from agriculture, forestry, urban waste and wastewater management, and various uses of chemicals, for example (EEA, 2020a, 2024b).

Combined, such activities exert a wide range of pressures on the marine environment including physical loss, damage and disturbance, enrichment with nutrients and organic matter, contamination with hazardous substances, biological disturbance (including the introduction of non-indigenous species) and selective extraction. All of these pressures can interact and be exacerbated by the effects of climate change, further increasing threats to Europe’s ecosystems, food security, public health and the economy (EEA, 2020a, 2024b).

As such, the environmental state reflects the cumulative impacts of historic and current activities. In the context of achieving good environmental status under the Marine Strategy Framework Directive (MSFD) and good ecological status under the Water Framework Directive, any new activity should be considered in line with the requirements of these directives.

Map 1. Europe’s marine areas’ relative vulnerability to climate change (European Marine Climate Change Index (EMCCI))

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Careful implementation is needed to avoid that such projects introduce additional environmental pressures, even if they provide overall life-cycle improvements and lower the need for fossil fuels across the EU economy (EEA, 2021). Across their various phases — exploration, transportation, construction, operation and decommissioning — offshore wind projects, like most offshore activities, exert a range of impacts on the marine environment (Bergström et al., 2014).

These impacts may include habitat disturbance, degradation or loss, noise pollution, emissions of vibration and electromagnetic fields, increased primary production, and harmful effects on various species, which ultimately impacts ecosystem resilience (Daewel et al., 2022; Galparsoro et al., 2021, 2022). It can also lead to the creation of new habitats, with both positive and negative potential effects on the local environment.

Importantly, offshore installations can also provide positive benefits to the marine environment by forming artificial reef environments, which can provide some shelter for commercially exploited fish species when paired with restrictions on some types of commercial fishing activities. The red-listed tube-forming worm Sabellaria spinulosa has for example been observed establishing new colonies at turbine foundations in the North Sea. Similarly, offshore windfarms can have positive effects on local cod (Gadus morhua) populations (Gimpel et al., 2023). Offshore wind farms thus offer an opportunity for exploring synergies and co-existence between maritime structures and nature, especially if bottom-contacting fishing gear is excluded from these areas. Moreover, active restoration measures may be combined with offshore renewable energy projects (e.g. reef restoration) in view of maximising the potential benefits for biodiversity and contributing to biodiversity targets.

Map 2a. Ecological sensitivity index for wind power (left); Map 2b combined effects of human activities and pressures (right)

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For offshore wind generation, shallow areas also have a higher value than more distant, deeper areas due to lower costs in construction and maintenance, and a smaller loss of energy (Map 3). Some areas are also more attractive due to prevailing wind conditions or dominant seafloor substrates. As such, the industry has prioritised the placement of offshore wind turbines based on the lowest levelised cost of energy (LCOE; the cost of electricity production over the lifetime of the project) possible, though it expects LCOE to decrease significantly as more turbines are deployed (WindEurope, 2019). From an offshore renewable energy production perspective, coastal areas are more cost-effective localities compared to further offshore (Map 3).

Map 3. Relative lowest Cost of energy for offshore wind in northern Europe

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From this perspective, some marine areas are more suitable for the placement of offshore wind than others (Map 3). LCOE increases with distance from the shore and certain areas have better wind conditions, more suitable substrates or are simply closer to the end user than other areas. In the context of limited available space in coastal zones, building new turbines further offshore and into deeper waters will also require going from bottom-fixed turbines to floating turbines. As the industry matures over the longer term the added costs of going further offshore and into deeper waters may be reduced.

Overall, the coastal zone can be considered more sensitive to the installation of offshore turbines and other human activities than the areas further from the shore as these are already impacted by other activities and their cumulative pressures (Map 2a and Map 2b) (EEA 2020a).

Maritime spatial planning: key for balancing activities to ensure sustainability

With a need to ensure that reaching the EU’s energy targets is balanced with meeting conservation and restoration objectives, an integrated approach that accommodates the potential conflicting pressures is required.

The urgent imperative to achieve EU energy and climate neutrality objectives while protecting marine biodiversity therefore necessitates careful planning and use of maritime space, which includes the use of the best available scientific knowledge and data-driven analysis.

Such an approach is crucial for assessing the specific spatial requirements of various activities in diverse ecosystem features, including habitats and species. This is essential not only for existing activities but also to mitigate potential conflicts among stakeholders when offshore wind and nature conservation efforts potentially expand into waters traditionally used by others — such as for maritime transportation, fisheries and recreation.

Maritime spatial planning is an essential tool to reduce pressures to the marine environment and conflicts between sea users. It reconciles nature conservation with economic development. In certain areas of Europe’s seas, the multiple use of space for different activities will become a necessity. To help sectors work together, the European Commission launched the first ever international compendium of multi-use examples. This dynamic tool showcases good practices of multi-use in the EU and around the world.

Regarding the significant expansion of offshore wind energy and marine protection, questions of trade-offs may arise relating to maritime activities and policy ambitions. Traditional fishing grounds that have been used for generations may be restricted and shipping routes could be shifted to potentially less efficient ones. Ecological considerations — such as alterations to seabed habitats, movements of marine mammals and bird flight patterns — require mitigation strategies. These complexities underscore the need for inclusive stakeholder engagement — which includes citizens — and interdisciplinary approaches when developing sustainable energy transitions at sea. Coherent data and information gathering initiatives are also needed (ICES, 2024).

Some past experience underlines this imperative. In a few projects for example, in the Kattegat, the sea area between Jutland in Denmark and the western coast of Sweden, the initial placement of offshore wind turbines has resulted in targeting of specific habitats. This is probably because environmental impact assessments were done on an individual project basis and not across the multiple project areas used for deployment of wind farm areas (Cameron and Askew, 2011). This underlines the critical importance of applying an ecosystem-based approach that has, since 2018, been a requisite part of maritime spatial planning, but also the importance of conducting an appropriate strategic environmental assessment, taking into account environmental considerations at planning level.

In 2021, the European Commission published guidelines for implementing an ecosystem-based approach in maritime spatial planning (EBM), recognising it as necessary to achieve sustainability (Box 3) (EC, 2021b).

In practice, implementing an effective ecosystem-based management (EBM) approach involves aligning EU maritime spatial plans and tools with the goals of the EU Marine Strategy Framework Directive and stakeholder needs, to ensure a balanced use of Europe’s seas across all sectors. Such an approach allows for the exploration of co-existence, nature-inclusive designs for offshore structures (i.e. designs that enhance nature in the space occupied by the maritime structure), and the use of targeted subsidies to promote sustainable developments.

One example of such an approach has been deployed for maritime spatial planning and public-sector decision making in Sweden. The SYMPHONY project demonstrated how it is possible to inform a stakeholder dialogue on the use and planning of the seas by balancing ecosystem features, pressures, and human use (Box 4).

To achieve sustainability, such approaches will be needed at larger geographic scales spanning national waters and balanced across regional seas as concluded by the first implementation report of the Maritime Spatial Planning Directive (EC, 2022d). The European Marine Observatory and Data Network (EMODnet) is supporting this more regional and digital approach as well as the various EU sea-basin strategies and macro-regional strategies. From an EU perspective the Greater North Sea Basin Initiative (GNSBI), established in November 2023, aims to strengthen cooperation on various aspects of maritime spatial planning. These include the provision of a regional platform for spatial integration for better alignment with the MSP, developing efficient management processes, and coordinating sectoral interests across boundaries. With these aspects in place, EU countries will be able to address the spatial and ecological challenges of the Greater North Sea basin (EC, 2023).

It is important to allocate sufficient time for thorough, data-driven analyses of the environmental impacts at both the project and ecosystem levels as the competing demands upon Europe’s seas continue to grow. Prioritising information-based maritime spatial planning that links the objectives and targets of the EU legislative framework should necessarily reflect the broad range of stakeholder needs. An ecosystem-based approach should be applied to manage all human activities in the marine environment. Such an approach is essential for handling the intertwined challenges of halting biodiversity loss, mitigating climate change and ensuring sustainable maritime activity — particularly in sensitive coastal regions.

Consultations and the coordination of maritime spatial plans at the regional level are also crucial. This ensures coherent and sustainable planning across the EU's sea basins and should also promote comprehensive assessments of the cumulative impacts from marine activities at the sea-basin level.

In conclusion, future competing demands upon Europe’s marine environments will necessitate trade-offs to be properly considered. Maritime spatial planning is essential to ensure a balanced use of marine resources through an ecosystem-based approach as defined by EU legislation.